Dropout fuse construction



June 3, 1952 s. 1. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 1 Filed April 22, 1946 jnvenior (yard! ZL'ncZeZZ June 3, 1952 s. l. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 2 Filed April 22, 1946 Sigum MA J1me 1952 s. l. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 3 Filed April 22, 1946 jnz/enz'or. Ward] Zindell June 3, 1952 s. 1. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 4 Filed April 22, 1946 Jnue-rzor: ardjlindell.

RUBBER June 3; 1952 s. 1. LlNDELL DROPOUT FUSE CONSTRUCTION- 8 Sheets-Sheet 5 Filed April 22, 1946 no 1 76 0 5 55 M W m m 0/0 w a m aw 39 0 u U mm 5 w mm fl June 3, 1952 s. l. LlNDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 6 Filed April 22, 1946 n a s w a M wmw wmm Z w w @ww m umdgfiwxiiii H V a MIIIII- m k L .w fl Flip 7 m w M 0 m June 3, 1952 s. l. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 7 Filed April 22, 1946 Qrdf zifzdelz.

WEWMM J1me 1952 s. I. LINDELL DROPOUT FUSE CONSTRUCTION 8 Sheets-Sheet 8 Filed April 22, 1946 lindelzl. W

Patented June 3, 1952 DROPOUT FUSE CONSTRUCTION Sigurd I. Lind'ell, Chicago, Ill., assignor to S & Electric Company, a corporation of Delaware Application April 22, 1946, Serial No. 663,834

13 Claims. (Cl. 200-114) This invention relates, generally, to dropout fuse constructions and it has particular relation to dropout fuses for use with high voltage electric power systems operating at voltages of the order of 115 kv. at 60 cycles.

The present invention has to do particularly with the provision of means for providing an air gap in the circuit between at. least one of the fuse tube terminals and its associated line terminal after the fuse blows for a fuse of the type disclosed in the copending application of Sigurd I. Lindell and Charles H. Baker, Serial No. 663,832, filed April 22, 1946, now abandoned. The dropout features of the present invention are also employed in a fuse construction in which isincorporated the particular contact clip arrangement disclosed in the copending application of Sigurd I. Lindell, 'Serial No. 663,833, filed April 22, 1946, now Patent No. 2,484,839, dated October 18, 1949.

As indicated, the dropout fuse constructionin which the present invention isembodied isparticularly designed to operate-in assystem energized at a voltage of 115 k-v. However, it-willbe understood that the principles of this invention canbe employed in the construction of .fusessfor other voltages. In afuse of this type it .is-necessaryto provide a relatively great spacing, between the fuse tube terminals andtotakeparticular precaution. with respect to-thewmanner in which, these terminals are arranged with respectto the fuse tube, so that fiashover of these terminals or. between either of. them and conducting parts within the fuse tube-isprevented asaresult of certain over voltage conditions incident to fuse operation which-mayoccur under circumstances where the transient recovery voltage, is several times greater than the normal frequency recovery voltage.

One particular embodiment ofthe. invention designed for thisvservice includes a fuse tube which, together with theoperating mechanism therein and terminals and their: fittings atthe ends, has a. weight in the neighborhood offrom 40 to 50 pounds. The construction must-be such that the fuse can be mounted out-.of-doors where it is subjected to the weather and where itis not feasible to provide any protection or shielding from the elements. Moreover, the construction must be such, that after the fuse has been in the closed position for a relatively long time, such as several months or years, itwill drop promptly to the open position after the circuit hasbeen interrupted and the arc extinguished.

Accordingly, an object of the present invention, generally stated, is to provide a dropout fuse construction which shall be simple, efficient and positive in operation regardless of weather conditions and the time that it has been in service and which may be readily and economically manufactured' and installed. v

Another object is to provide for automatically dropping out of a circuit a fuse tube on the occurrence of a fault in the circuit, the fuse tube together with its fittings having a weight of th order of from 40 to pounds.

A further object is to provide for positively latching such a fuse tube in the closed position and for positively and automatically releasing the latch mechanism only after the arc incident to the blowing of the fuse has been extended and completely extinguished.

Still another object is to provide a weather tightconstruction for such a dropout fuse construction.

A still. further object is to maintain a circuit through the rod-like terminalwhich forms'a part of the circuit means interconnecting the fuse tube terminals while the former is being withdrawn within the fuse tube after blowing of the fusible means.

Another object is to provide for manually releasing the latch mechanism independently of the means that is provided for tripping thesame automatically as a result of blowing of the fusible' means.

Stillanother object is to guide'the' fuse tube in its mounting so that it cannotbe disengaged accidentally therefrom or thrown out ofalignment as itis' moved from and to the open position.

Another object is to provide a self aligning latch mechanism which is substantially independent of reasonable variationsin the center to center distances between the stationary'terminals as determined by the spacing on the line side of their insulating supports.

A' furtherobject isto preventthe accidental disengagement of'the fuse tube from its pivot mounting after it blowsand'when the fusetube in the open-position is so located that theforce of gravity is ineffective to prevent disengagement from the mounting, as men underhung fuse mounting.

Still another object is to interconnect the line terminals and the associated fusevtube terminalsof adropout fuse by. means of a generally U-shaped contact clip. mounted on the former and .a pair of pivoted contact links on the latter.

Other objects of thisinvention will; in part, beobvious and'in part appear hereinafterL' This invention is disclosed in the embodiments thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the constructions hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference can be had to the following detailed description taken together with the accompanying drawings in which:

Figure 1 is a view, in side elevation, of a dropout fuse construction in which the present invention is incorporated, the fuse tube being illustrated as being mounted vertically in the closed position;

Figure 2 is a view, in front elevation, of the fuse construction shown in Figure 1;

' Figure 3 is a view, in side elevation, at an enlarged scale of the latch mechanism for the fuse shown in Figures 1 and 2;

Figure 4 is a top plan view of the latch mechanism and contact construction shown in Figure 3, certain parts being shown in section to illustrate more clearly the details of construction;

Figure 5 is a top plan view of the lower contact clip construction, certain parts being shown in section;

Figure 6 is a view, in side elevation, of the lower contact clip construction;

Figures 7A-7B-7C, taken together, show a longitudinal sectional view through the fuse construction of Figure 1, the fuse being shown in the unblown condition;

Figures 8A-8B are views similar to Figures '7A-'7B, but showing the fuse in blown condition;

Figure 9 is a view, in side elevation, of the fuse construction shown in the preceding drawings mounted at an acute angle with respect to the vertical;

Figure 10 is a view, in side elevation, at an enlarged scale of the trunnion mounting for the fuse construction shown in Figure 9 together with the manually operable latch arranged to prevent accidental disengagement of the trunnion mounting when the fuse blows; and

Figure 11 isa detail sectional view taken along the line I l-l I of Figure 10.

Referring now particularly to Figures 1 and 2 of the drawings, it will be noted that the reference character It; designates a channel base that is vertically mounted and carries at its ends stacks of insulators H and 12, extending in a horizontal direction one above the other. At their outer ends the insulators H and i2 carry power line terminals l3 and i4 which, it will be understood, are arranged to be connected by suitable conductors into the circuit. The terminals I3 and I4 carry contact clips, shown generally at l5. and 16, which are arranged to be connected in a manner which will be described in detail hereinafter to fuse tube terminals H and I3 carried at the ends of a fuse tube 19. The reference character 2!! designates, generally, the fuse tube construction which includes the fuse tube I9 and the terminals I! and I8 at its ends.

The fuse construction is of the dropout type and is arranged to be latched in a closed position by a latch mechanism which is indicated, generally at 2|. The fuse construction 20 is hinged at its lower end so that, when the latch mechanism 2| is unlatched, it can fall under the influence of gravity and the spring action of contact clips I5 and it to the position shown by the broken lines in Figure 1. For this purpose the lower line terminal It is provided with a hinge extension 22 that projects forwardly thereof and has slotted openings 2 therein for receiving trunnions 25 that are integrally formed with and extend from a trunnion and pivot contact assembly or cradle 28 that i secured to the lower fuse tube terminal [8 and supports the same.

In Figures 3 and 4 of the drawings the latch mechanism 2! is illustrated in more detail. As there shown, the latch mechanism 2! includes a latch lever 32 which may be rockably mounted by a bolt 33 on the upper line terminal 13. A coil spring 34 surrounding the bolt 33 serves to bias the latch lever 32 in a clockwise direction. At its forward end the latch lever 32 carries a hook roller 35 behind which a latch roller 36 is arranged to be positioned to hold the fuse construction 23 in the closed position. The latch roller 33 is carried by a nose portion 31' that is formed integrally with an upper fuse tube holder which is indicated, generally, at 38. The upper fuse tube holder 38 surrounds the upper end of the upper fuse tube terminal I? and is held in place thereon by a retaining screw 39. The nose portion 37 has an inclined face 40 which, when the fuse construction 20 is moved toward the closed position, first engages the roller 35 and lifts the same together with the latch lever 32 sufficiently to permit the latch roller 36 to pass thereunder to the latched position shown in Figure 3. A stop pin 4|, threaded into the upper line terminal [3 through the bottom of the contact clip [5, serves to limit the inward movement of the fuse construction 26, the head of the retaining screw 39 on engaging the outer end of the stop pin 4| preventing further inward movement of the fuse construction 29.

With a view to releasing the latch roller 36 from behind the hook roller 35 a pry out lever 43 is mounted for rocking movement about the axis of the roller 35 on the latch lever 32. The pry out lever 43 is biased for movement in a clockwise direction by a leaf spring 44 that extends from the upper surface of the latch lever 32 near its rear end and bears against the underside of the pry out lever 43, as illustrated. A spring brace 44' is positioned underneath the leaf spring 44 and serves when the latter engages it to limit further downward movement of the adjacent end of the pry out lever 43. This end of the pry out lever 43 then is fulcrumed at this point and further counter clockwise movement thereof lifts the latch lever 32 and hook roller 35 to disengage the latch roller 36. A web 43', integrally formed with the pry out lever 43 limits the clockwise movement thereof by engaging the forwardend of the latch lever 32.

In order to move the pry out lever 43 in a counter-clockwise direction so as to raise the latch lever 32- and move the hook roller 35 out of engagement with the latch roller 36, the pry out lever 43 has bosses 45 extending oppositely therefrom on opposite sides as shown more clearly in Figure 4. Fingers '46, extending from a pull ring and trip member, indicated generally at 47, are arranged to bear against the bosses 45 and to move the same upwardly. The member 41 is rockably mounted by, a pin 48 which extends through ears 49 that, are integrally formed with the upper fuse tube holder 33.. The member 41 also includes an integrally formed ring 59 for receiving the hook of a switch stick ,to permit manual operation of the member 41 and tripping of the latch mechanism 21 *A coil spring 5L, surrounding the-pin, serves to normally-bias the member' fl for movement in'a counter-clockwise 'Whenit is desired to manually trip the latch mechanism 2 l the' hook em switch stick is in sertedfin' the ring Sll and the member 41 is rocked ina clockwise direction against "the-force f "the spring to lift the fingers 46 and thereby lift the "bosses 4 5 extending from the pry cut lever 43 previously: described; this 'lifts' the latch lever '32 and'thehookroller 35 is movedpu't 'of engagement with theflatch" rollerfi," whereupon the ruse construction free" terairto the posh tion shown by: the broken lines'in' Figures '1' of the r :1 .1 a U1. Ms 1 i 1 The latch mechanisml-l may be tripped also when the ruse constructionidblows. As'willbe Set forth in 'moiie fietail "hereinafter, w en the ruse construetion' Z'B'blows, a latch tube sawmc is slidably moi'infed the upper end Of the" fuse tube -I9,'moves"upwardly through a slight di tance. "rhe latch tube 5;: has; a angefit that "is movable "therewith and that "is arranged to en'- gage downwardly extending nose portions-that ar'e 'integrally formed with'thepry out lever? 43. Thisupward moveriientot the latch cute-"5 ers sutficient to rock the pry out let er 13" td substanc tially the sameenem" it is rocked the me ber l'ljjuslt described? As'aresult of the blowing of the fuse' constructiorr" 2' 0", the "hook r'oneifa i is liitedoutol thepath or the latch e 1 '6 d he use nst iwi qn 0 T h r- 11110.11" n im tted' i' l a l mi efif oe n er efi gre Wi h ino i n sh wnby' the bk f in s Y ,7 ure'. of the iew n s e. e mi n en l etion. f ener reierredFto, there is disclo d "in inore"complet'e detail the mannerin whic thecontact'clips' l5 a e n b ed. t t uee ub mina Hi and: I8 there indicated; the fuse "clips li and l6 are"oijduplicate"constructioii. Their cennection to the'fusetube terminalsflfl and'le' is essentially the same." Accordingly. the "same reference characters will be usedfor both herein as Tarasfis practicable. Indescribingthe construction and functioning' of the contact clips I 5 andfl 6 reference will now be had; particularly to Figures 3, 4, 5 and '6 o'ffthe drawings." 'A s thereillustrated, each oifthe contact 'clipslfi and lfi' incljudes a generally U- shaped, copper contact connector 531; which carries copper alloy contjact shoes 53 near I its outer ends. They are securedinplace by rivets 59. The contact; shoes 58' provideo'pposed contact surfac'estll which are biased; toward each other we generally U-shaped contactspring 6|, preferably formed oistainless steel. .Near its outer ends'the arnis oftheCQntactspringBI are provided with apertures; 62 forreceiving extensions 6 3 from the rounded'outer ends of guide pins 63 whichiztnd froin the contact shoes 58, as illustrated, 'The combinatio'nbtthe copper contact connector rend the contact spring 6| provides fofgood ele'ctrical conductivityffpr the contact clips "|'5 and 'lfiandatthesame timethe required degree of resiliency to urge the contact surfaces Sillof the contact shoes 5 8.jtoward each'other with the required pressure suflicient not only to assure the necessary contactpressure' but also, as will appear'hereinafter;'tofbias the fuse construction 2Q outwardly 'away froin the closed position thereof; The contactf'clip s l5 and J may be held inplate on" the lineterrniha'ls I 3' and H respecnew. by" suitable "cap tons 64 'which extend through a baseporticn of each of the springcontacts'E'I' andthehOntact springiia It' desiredthat'a'direct electrical connection be provided between thecontact shoes 53 and the outer surfaces of the associated fuse tube terminalsn and1'8." One'rea'sonKbrfthis to avoid the necessity of using'aflexibleshuntto complete the connection; For this purpose pivot contacts orcontact" of suitable conducting mate'- rial, suchas' 'brass, are pivotedonpins-Glfon the upper iuse'tube holder 38' and on the cradle .2.8. As set forth in mored etail in thecop'endingsapplicationbf Linde1l;"above referieditofthelinks 61' are loosely mounted'by their respective pins 68 so that; when thefuse construction mcoccupies the closed position, the 'inn'er "ends of. the links 61' will "bear against and intimately contact the adjacentportions of the surfaces ofsthefuse' tube terminals H and-1a; The rounded ends I [of the links 61 engage their respective contactsuri'aces 6 0 with a wiping-action when the fuse construction'"! 0 is 'movedto' the 'closedposition and disenengage the same with a'rolling' or rocking action. This rocking'or rolling" 'a'ction' overcomes any tendeny "to sticlg the presence of "corrosion, sleet "etc. and facilitates breaking-loose therefrom; I

It will be observed that the links 61 pivotally mounted as described; cooperate with their .respective sup orts inthe' manner of tog ie; The resilient force ofthe contact springfil isexerted through the links 5]. However/the construction is such that when thefuse 20 is 'movedto the closed position, the links'sfl are not moved. past the'centeifp sition of thetoggle; rather they tare always maintained 'on'-the "release "side of this position. "Consequently, "the contact spring H in each caseffunctions 'to urge th'e'iuse construction '20 "away from'the closed position; It is held in the closed position only by the latch mechanismzL so. a a. *With a view to guiding the links BI-intooperative positions between the contact shoes 58; pivot contact springs 13 are'secure'd as bysciews' 14; to the respective upper fuse tubeholdersl and'the cradle 28'. The outer curved ends 15 of' the springs 13 bear against'the links 61 andnorinally urge them tdward each other'a'bout their-respec tive pivot pins'68. Stop pins- 16 are locatediri'the links 61 to cooperate'with webs; such asthe'webs l'T, Figure'4, for limiting the movement of the linksffi'l' when they are'bllf'of engagementwith the contactshjoes58j, As shown in Figures 5 and 6 0i the drawings, the cradle 28 is secured to the lower fuse tube terminal [8 by means of suitablecap bolts '80. Extending downwardlyirom the'lower fuse tube terminalj I8 is acondenser shell 8| which, as will hereinafter appear,' contains'a condenser" for cooling and condensing the products of the' are when the fuse construction zllfblows.

It is desired that the fuse construction 20 fall to substantially 45 when it blows. This isillustr'atedin Figure 1 of the drawings." In order to cushion the shock incident to stopping the fuse tube l9 in this position a cylindical rubber bumper 82 is fastened to the hinge extension 22', 'a's's'h'own on Figures 5 and B, and its outer 'end is engaged by the condenser shell '8lwhen' the fuse tube ll! drops to the open position; With a view to preventing the trunnions 26 from accidentally hopping out" of the slotted openings 24 in the hing'eextension 22, the cradle 28 has cam portions 26' integrally formed therewith which coope'ratewith bosses" 221, integrally formed with the hinge extension 22. Extensions 8| from the hinge extension 22 serve to guide the condenser shell 8| therebetween during the dropout action and likewise prevent such accidental disengagement.

The details of the fuse construction and the particular reasons for certain of them are set forth more fully in the copending application of Lindell and Baker referred to hereinbefore. Accordingly, only a general description of the fuse construction 20 will be set forth herein. For this purpose reference will now be had to Figures 7A-7B-7C and Figures 8A-8B of the drawings.

The fuse tube I9, there illustrated, is formed of illustrating material such as Bakelite. Since this material cannot satisfactorily withstand the normal frequency recovery voltage after the fuse has blown, it is necessary to drop it out of the circuit and provide an air gap therein.

About midway of the length of the fuse tube I9 its internal diameter is reduced, as indicated at I I8, for the purpose of providing a section which has increased resistance to bursting pressure. With a View to providing an arcing passageway from whose surface an arc extinguishing medium can be evolved, cakes I I9 of solid arc extinguishing material are positioned along the bore of the reduced diameter section II8. These cakes I|9 are annular in form and together provide a continuous bore I20 in which the arc may be drawn and extinguished. Various solid arc extinguishing materials may be employed such as boric acid or magnesium borate. The reduced section H8 is threaded as indicated at I2|,- for receiving the cakes N9 of solid are extinguishing material which are molded in place cake by cake therein.

At each end of the column of cakes I I9 of solid arc extinguishing material there is provided a reenforcing ring of suitable insulating material such as fiber. One of these is indicated at I21 at the upper end of Figure 1B and the other is indicated at I28 at the lower end. The reenforcing ring I28 is flared outwardly to facilitate the outwardward flow of the products of the are.

Moveably mounted within the bore I20 in the cakes II9 of solid arc extinguishing material and substantially filling the same is a rod-like terminal I29. At its upper end the terminal I29 is provided with a contact tip I30 which is arranged to be engaged by contact fingers I3I, the upper ends of which are turned inwardly and biased inwardly by a garter spring I32. The contact fingers I3| extend upwardly from a contact fitting I33 which, in part, serves to hold the reenforcing ring I21 in place.

The electrical connection between the upper fuse tube terminal I1 and the contact fingers I3I is provided by a conducting tube I34 of brass or other suitable conducting material- It will be noted that the lower end of the conducting tube I34 is threaded onto the contact fitting I33 and that a nut I35 is threaded onto the upper end thereof and also is threaded into the fuse tube terminal I1. This is shown in Figure 7A. A lock nut I36 serves to hold the contact nut I35 in place.

When the fuse blows, it is desired that the rodlike terminal I29 be moved rapidly through the bore I20 in order to extend the arc therein and permit the heat thereof to evolve an arc extinguishing medium, such as water vapor, from the bore I26 so as to deionize the arc space and assist in extinguishing the arc. For this purpose a helical compression spring I31 is located within the connector tube I34 and bears against the fitting I33 and the under side of a spring seat I38 which is secured to the lower end of a compression tube I39 that may be formed of brass. The compression tube I39 carries a base I40 at its upper end from which a stud I42 depends. 0n opposite sides of the lower end of the stud I42 links I43 are pivoted by a pin I44. Between the links I43 a pulley I 45 is rotatably mounted on a pin or shaft I46.

A cable connector assembly, shown generally at I49, extends over the pulley I45 and provides both mechanical and electrical connection to the rod-like terminal I29 for effecting retraction thereof and also for maintaining electrical circuit connection thereto while it is moving through the bore I20 and after the contact tip I30 is moved away from the contact fingers I3I. The cable connector assembly I49 comprises a core I50 formed of a large number of strands of relatively fine wire, such as copper wire, and an outer sheath I 5| that is formed by a closely wound coil spring preferably of stainless steel. One end of the cable connector assembly I49 is connected to the contact tip I 30 of the rod-like terminal I29, as shown in Figure 7B, while the other end is connected to a strap or cable link I52. The lower end of the strapor link I52 is secured, as by rivets I53, to the contact fitting I33.

When the fuse blows, as will be described hereinafter, the spring I31 is released and it moves the compression tube I 39 upwardly, carrying with it the pulley I45. Because of the mechanical arrangement thus provided, the rod-like terminal I29 moves at twice the speed that the compres sion tube I39 is moved and its extent of movement is twice as great. The compression tube I39 carries with it the base I40 which moves upwardly until it engages a cap I54 that is secured to the upper end of the latch tube 52. It will be recalled that the upward movement of the latch tube 52 is accompanied by a corresponding upward movement of the flange 53 to operate the pry out lever 43 and effect unlatching of the latch mechanism 2| so that the fuse construction 26 can fall to the open position. The latch tube 52 moves upwardly until a shoulder I55, Figure 7B, on the spring seat I38 engages a shoulder I56, Figure 7A, on the inside of a stop tube I51. The engagement of the shoulders I55 and I56 is illustrated in Figure 8A. The stop tube I 51 is secured to a depending annular flange I58 that is integrally formed with the upper fuse tube holder 38 which, it will be recalled, is secured by the retaining screw 39 to the upper fuse tube terminal I1. The stop tube I51 is held in place in the flange I58, in part, by a sleeve I59 over which the lower end of the tube I51 is rolled and which bears against the under side of the flange I58. Thus the stop tube I51 constitutes an extension of the upper fuse tube terminal I1 and, since it is coextensive with the latch tube 52, a weathertight construction is provided. The latch tube 52 is held in the position shown in Figure 7A of the drawings by a coil compression spring I62 which is located between the tubes 52 and I51 and at its lower end bears against the upper end of a tubular extension I63 from the fiange 53 and at its upper end against the under side of collar I64 which is secured to the upper end of the stop tube I51.

The upper fuse tube holder 38 is provided with integrally formed ears I65 and I66 on opposite sides between which the pivot contact links 61 are mounted by the pins 68. This mounting is described in more detail in the copending application of Lindell, previously referred to. As shown'in Figure 7A. the upper fuse terminal I1 is secured to the upper end of the fuse tube I9 by suitable screws I61.

For the reasons set forth in the copending application of Lindell and Baker, the fuse tube terminal I8 is extended by an exhaust tube I18 of suitable conducting material, such as brass within the fuse tube I9. As illustrated in Figures 7B- 7C, the exhaust tube I18 is positioned within the fuse tube I9 at its lower end. Its inturned upper end bears against the fiber retaining ring I28 and serves to hold the same in place. At its lower end. the tube I18 is connected to the lower fuse tube terminal I8 by a nut |1I which, as shown in Figure 7C, is threaded onto the lower end of tube I18 and also is threaded into the fuse tube terminal I8. A lock nut I12 holds the nut III in place.

As shown in Figure 7B, the exhaust tube 18 carries a narrow bridge or fuse element support I13 nearits upper end from which a rod-like terminal I14 extends upwardly. A tubular adapter I15 and nuts I16 cooperate to hold the terminal I14 in, place on the bridge I13 and provide good electrical and mechanical connection therewith. The terminal I14 is connected to the rod-like terminal I29 by a coiled fusible element I11, preferably of silver, and a strain element I18, preferably a high strength alloy wire such as Nichrome or Chromel. wire. derstood that the bridge I13 is securely fastened to the exhaust tube I18 so that it may have mechanical and electrical connection therewith.

As shown. in Figure 7B, the lower fuse tube 881?- minal I8 may be secured to the lower end of the fuse tube I9 by suitable screws I8I.

The exhaust tube I18 has certain additional functions. It is of such cross-section that it will carry a normal load current of the order of 200 to 300 amperes. It has sufficient strength to serve as a strut and reenforce the lower end of the fuse tube I9 and strengthen the same thereby preventing fracture of the same on dropping out. As a result, the fuse tube I9 is well able to withstand the relatively severe mechanical shock incident to its dropping out and being arrestedby the bumper 82' in the position shown by the broken linesin Figure 1 of the drawings.

In order to mount the condenser shell 81 a reducer fitting I82 is threaded into the lower end of the lower fuse tube terminal I8 and the shell BI is threaded thereon, as illustrated in Figure '13. Within the condenser shell 8| is a condenser assembly I83 which serves to cool and condense the products of-the arc resulting from the blowing of the fusible and strain elements I11 and I18. In general thecondenser assembly I83 comprises spirally wound and spaced apart metal strips as described more fully in Triplett Patent No. 2,379,200. It is held inplacein the shell 8| by threepins I83 (only two being shown) that extend upwardly from a valve seat I84.

It is desirable that the condenser shell 8| be closed to the atmosphere except when the fuse blows. This prevents the introduction of extraneous matter to the interior of the fuse. For this purpose the valve seat I84 is threaded into the lower end of the condenser shell 8| and a valve. cover I85 is arranged to cooperate there.- with. The valve cover I85 is slidably mounted on the valve seat- I84 by a stud I86 and is held in the closed position by a coil compression spring I81 which reacts between the upper surface of the valve seat I84 and a nut I88 at the upper end It will be un' 10 of thestud I86. When sufilcientpressure is generated within the condenser shell-8| on the blow.- ing of the fuse, the are products expand through. apertures I89 of the valve seat I84, lift the valve cover I'from the valve seat I84 and are exhausted into the atmosphere.

In order to place the fuseconstruction 28 in the closed position, it is first manually placed, as shown by the broken lines in Figure 1, with the trunnions-28 in the slotted openings 24 inthe hinge extension 22 and with the condenser shell 8| resting against the rubber bumper .82.. The hook of a switch stick is inserted in the ring .58 and the fuse construction is thereby swung to the closed position where the latch roller 36 is-positioned behind the hook roller 35 andthe pivot contacts or contact links 81 are in engage-q. ment with their respective contact shoes 58 of. the contact clips I5 and I6. The internal arrangement of the parts within the fuse tube I9 in the unblown condition is illustrated in Figures 7A-7B-7C of the drawings.

As long as a fault does notv occur on the system and in the circuit in which the fuse construction 28 is connected that exceeds thatfor which the fusible element I11 is designed to blow, this condition-is maintained. Howevenon' the occurrence of a fault of a predetermined character, the fusible element I1,1,melts,.thereby transferring the entire current flow to the strain element I18 which promptly melts and releases the rod-like terminal I29 for movement through the bore I28 under the influence of the coil compression spring I31. Although the contact tip I38 of the rod-like terminal I29 moves out of engagement with the contact fingers I3.|, a circuit to the rod-like terminal I29 is maintained through the connector assembly I49, conducting strap I52 and conductor tube I34 to the upper fuse tube terminal I1. The resulting arc is drawn between .the terminals I29 and I14 within the bore I28 where the heat thereof evolves water.

vapor, ina manner well known to those skilled in the art which assists in extinguishing thearc and deionizing' the arc space. The products of the are are blown through the exhaust tube I18 and over the stack I83 of condenser plates." If sufiicient pressure is generated, the valve cover I85 is lifted to permit the products of the are. to be exhausted through the apertures I89 to the atmosphere.

- While the rod-like terminal I29 is being retracted through the bore I28, the latch. mechanism 2| holds the fuse tube I9 in the closedposition. It is not until the base I48 engages the cap I54 that there is any operation of the latch mechanism. This engagement takes place only near the end of the stroke of the rod-like terminal I28 and results in a slight upward movement of the .latch tube 52'. This upward movement is arrested by engagement of the shoulder I55 on the spring ring I88 with the shoulder I56 on the stop tube I51. As described hereinbefore, the latch tube 52 in its upward movement carries with it the flange 53 which causes the pry out lever 43 to rock in a counterclockwise direction, as viewed in Figure 3, until it is arrested by the spring brace 44. Thereafter'it lifts the hook roller 35 sufficiently with respect to the latchroller 36 so that the latter disengages the former and the fuse tube. I9 is then free to fall to the open position. Its movement to the open position is initially assisted by the inherentresiliencyof theU-shaped contact clips I5 and I6 which,.-ac.t-. ing through the contact links 61, serve to urge 11 the fuse tube I9 outwardly with respect to the line terminals I3 and I4. This dropout action is positive, even in the presence of corrosion, sleet etc. because of the particular arrangement of the contact clips I5 and I6 and the links 61.

.After the fuse construction 29 has dropped out as a result of the occurrence of a fault on the system, the upper fuse tube holder 38 and the trunnion and pivot contact assembly or cradle 28 are removed from the respective fuse tube terminals I7 and I8 and are assembled on the corresponding fuse tube terminals of an unblown fuse. The reassembled fuse is then reconnected into the circuit as previously described.

As shown in Figure 9 of the drawings the fuse construction 29 can be mounted in an under hung position, for example at an angle of about from the vertical and, when it drops out, it occupies a position which is substantially horizontal. For this purpose a channel base I92 may be mounted at the desired angle and may be arranged to carry insulators I93 and I94 for supporting line terminals I95 and I96 at the lower ends which correspond to the terminals I3 and I4 as shown in Figure l. A conductor I91, supported by an insulator I99, which is one of a stack of insulators, may be connected to one line terminal I95. The other line terminal I96 may have a conductor I99 connected thereto.

The lower line terminal I96 may be provided with a hinge extension 299 that is shown at an enlarged scale in Figures 10 and 11. The hinge extension 299 has slotted openings 29I for receiving the trunnions 26 of the cradle 28. Each slotted opening 29I has a reentrant portion 292 in which the associated trunnion 26 fits.

Now when the fuse construction 29 is mounted as illustrated in Figure 9 and after it drops out into the position shown by the broken lines, it is quite likely that it will accidentally jump out of the slotted openings 29I and fall to the ground. It is to avoid this accidental disengagement of the trunnions 26- from the hinge extension 299 that the manually operable latch mechanism shown in detail in Figures 10 and 11 is provided.

As there shown a latch shaft 293 extends through arms 294 which form a part of the extension 299. At one end of the shaft 293 a latch lever 295 is secured, as by a transverse pin 295. The latch lever 295 has an integrally formed pull ring296 for receiving the hook of a switch stick to permit operation of the latch lever 295 from one position to another.

The latch lever 295 has an integrally formed cam portion 291 which, in the latched position shown in Figure 10 of the drawings, cooperates with the associated trunnion 26 to prevent the same from disengaging the hinge extension 299. A stop portion 299 is also formed integrally with the latch lever 295 and cooperates with a rectangular pad 299, carried by the hinge extension 299, for limiting movement of the latch lever in a clockwise direction as viewed in Figure 10. The cam portion 291 also cooperates with pad 299 to limit the extent through which the latch lever 295 can be rocked toward the unlatched position.

At its other end the latch shaft 293 carries a lock cam 2I9 which is similar in configuration to the cam portion 29? and stop portion 298 of the latch lever 295. Its cam portion cooperates with the trunnion 29 associated therewith for preventing it from hopping out of the slotted opening 29I in the hinge extension 299 in which it is located on blowing of the fuse.

In order to automatically position the cam portion 291 of the latch lever 295 and the lock cam 2! in either the locked or unlocked position a latch positioner or cam 2II is secured, as by a pin 2I2 to the shaft 293 midway its ends and it has cam surfaces 2I2 and 2I3 that are arranged to be engaged by a leaf latch spring 2! one end of which is secured to the hinge extension 299. It will be understood that the leaf spring 2l4 serves to hold the shaft 293 in either of its alternate positions, thereby making it unnecessary to position the cam sections accurately for cooperating with the trunnions 25 to hold them in place or in the unlatched position to permit removal of the fuse construction 29.

It will be noted that the portion of the cam 2II on the opposite side from the surface 2I2 lies along the condenser shell 9| when the fuse 29 is in the closed position. Thus the latch lever 295 cannot be moved accidentally to the unlatched position as long as the fuse 29 remains closed. Moreover, this portion of the cam 2II cooperates with the condenser shell 9| to move the latch lever 295 to the latched position when the fuse 29 is swung to the closed position.

The hinge extension 299 has inwardly projecting bosses 229 which cooperate with cams 26' to hold the trunnions 26 in the slots 29I while the fuse 20 is being moved to or from the closed position. Ears 22I integrally formed with the terminal extension 299 serve to guide the condenser shell 8| and thereby the fuse 29 into final engagement with the bumper 92.

Since certain further changes can be made in the foregoing constructions and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

1. A dropout fuse construction comprising, in combination, a pair of stationary line terminals, a fuse tube, terminals at the ends of said fuse tube, means pivotally mounting said fuse tube near one end whereby the same can be moved to the closed position with the terminals thereof in engagement with said line terminals and can fall under the influence of gravity to the open position away from at least one of said line terminals, latch means mounted near the other end of said fuse tube for holding the same in the closed position, a tubular latch release member slidably mounted on said other end of said fuse tube, a compression member slidably mounted within said fuse tube, spring means biasing said compression member toward said latch release member, and circuit means including fusible means within said fuse tube interconnecting said fuse tube terminals and restraining said spring means, said spring means being released on blowing of said fusible means and acting to move said compression member into operative engagement with said tubular latch released member whereby the same is moved to release said latch means.

2. The invention, as set forth in claim 1, wherein the compression member is movable through an extent substantially greater than the extent that the same eifects movement of the tubular latch release member to extend and extinguish the arc incident to the blowing of the fusible means before unlatching movement of said latch means is initiated.

3. The invention, as set forth in claim 1, wherein the fuse tube is hinged near its lower end and the upper end of the tubular latch release member is closed and the latter is coextensive with an extension of the fuse tube whereby a weathertight construction is provided when the fuse tube occupies either the closed or open position.

4. The invention, as set forth in claim 1, wherein the tubular latch release member is closed at its outer end and is telescoped with a tubular stop member secured to and extending outwardly from the associated fuse tube terminal whereby a weathertight construction is provided,

5. The invention, as set forth in claim 1, wherein the tubular latch release member is closed at its outer end and is telescoped with a tubular stop member secured to and extending outwardly from the associated fuse tube terminal whereby a weathertight' construction is provided, and a coil compression spring is located between said tubular latch release member and said tubular stop member and biases the former to the latched position.

6. The invention, as set forth in claim 1, wherein the circuit means also includes a rod-like terminal that is withdrawn by the spring means on blowing of the fusible means to extend the arc incident thereto and means are provided for maintaining the circuit through said rod-like terminal while the same is being moved by said spring means.

'7. The invention, as set forth in claim 1, wherein the latch means includes a latch lever pivoted on the adjacent line terminal, a hook roller carried thereby, a latch roller carried by an extension of the adjacent fuse tube terminal and adapted to cooperate with said hook roller to hold the fuse tube in the closed position, a pry out lever pivoted on said latch lever, and the tubular latch release member has a flange arranged to engage and rock said pry out lever to disengage said rollers and permit said fuse tube to fall to the open position when the fusible means blows and the spring is released to move said tubular latch release member to the unlatching position thereof.

8. The invention, as set forth in claim 1, wherein the latch means includes a latch lever pivoted on the adjacent line terminal, a hook roller carried thereby, a latch roller carried by an extension of the adjacent fuse tube terminal and adapted to cooperate with said hook roller to hold the fuse tube in the closed position, a pry out lever pivoted on said latch lever, the tubular latch release member has a flange arranged to engage and rock said pry out lever to disengage said rollers and permit said fuse tube to fall to the open position when the fusible means blows and the spring is released to move said tubular latch release member to the unlatching position thereof, and manually operable means are provided for moving said pry out lever to its unlatching position independently of said tubular latch release member.

9. The invention, as set forth in claim 1, wherein the fuse tube in the closed position is disposed at an acute angle away from the vertical and manually releasable locking means cooperate with the pivot mounting means to prevent accidental disengagement thereof when said fuse tube drops out on blowing of the fusible means.

10. The invention, as set forth in claim 1, wherein the fuse tube in the closed position is disposed at an acute angle away from the vertical, the pivot mounting means comprises trunnions on said fuse tube and substantially horizontal slots terminals in insulated spaced relation, a fuse tube, terminals at the ends of said fuse tube, separable contact means for interconnecting said line terminals and said fuse tube terminals, means pivotally mounting said fuse tube near one end whereby the same can be moved to the closed position with said contact means in engagement and can fall under the influence of gravity to the open position whereupon said contact means are separated, latch means mounted near the other end of said fuse tube for holding the same in the closed position, circuit means including fusible means within said fuse tube interconnecting said fuse tube terminals and arranged to unlatch said latch means on blowing of said fusible means to permit said fuse tube to fall to the open position, detent means movably mounted on the'lower line terminal and cooperating'with said pivot mounting means to prevent accidental disengagement thereof when said fuse tube drops out on blowing of said fusible means, a manually operable arm extending from said detent means arranged and adapted to be engaged by a live line tool from a remote point for moving said detent means out of cooperating relation with said pivot mounting means, and cam means operatively connected to said detent means and cooperating with said fuse tube for automatically resetting said detent means in locking position with respect to said pivot mounting means when said fuse tube is restored to the closed position.

12. A dropout fuse construction comprising, in combination, a pair of stationary line terminals in insulated spaced relation, a fuse tube, terminals at the ends of said fuse tube, separable contact means for interconnecting said line terminals and said fuse tube terminals, means pivotally mounting said fuse tube near one end com prising trunnions on opposite sides of said fuse tube and substantially horizontal slots on the associated line terminal whereby the same can be moved to the closed position with said contact means in engagement and can fall under the influence of gravity to the open position whereupon said contact means are separated, latch means mounted near the other end of said fuse tube for holding the same in the closed position, circuit means including fusible means within said fuse tube interconnecting said fuse tube terminals and arranged to unlatch said latch means on blowing of said fusible means to permit said fuse tube to fall to the open position, a shaft rockably mounted on said line terminal about an axis transverse to the longitudinal axis of said fuse tube, detents fast on said shaft cooperating with said trunnions to prevent accidental disengagement thereof from said slots said fuse tube drops out on blowing of said fusible means, and a manually operable arm extending from said shaft for rocking the same to move said detents out of cooperative relation with said trunnions to permit removal of said fuse tube.

13. A dropout fuse construction comprising, in combination, a pair of stationary line terminals in insulated spaced relation, a fuse tube, terminals at the ends of said fuse tube, separable contact means for interconnecting said line ter-'- minals and said fuse tube terminals, means'pivotally mounting said fuse tube near one end comprising trunnions on opposite sides of said fuse tube and substantially horizontal slots on the associated line terminal whereby the same can be moved to the closed position with said contact means in engagement and can fall under the influence of gravity to the open position whereupon said contact means are separated, latch means mounted near the other end of said fuse tube for holding the same in the closed position, circuit means including fusible means within said fuse tube interconnecting said fuse tube terminals and arranged to unlatch said latch means on blowing of said fusible means to permit said fuse tube to fall to the open position, a shaft rockably mounted on said line terminal about an axis transverse to the longitudinal axis of said fuse tube, detents fast on said shaft 00- operating with said trunnions to prevent acci-' dental disengagement thereof from said slots when said fuse tube drops out on blowing of said fusible means, a manually operable arm extending from said shaft for rocking the same to move said detents out of cooperative relation with said trunnions to permit removal of said fuse tube, and

a latch positioner in the form of a cam fast on said shaft intermediate said detents for cooperation with said fuse tube to reset automatically said detents in latching position with respect to said trunnions when said fuse tube is restored to the closed position.

SIGURD I. LINDELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,864,283 Steinmayer June 21, 1932 2,185,193 Hanson Jan. 2, 1940 2,247,700 Ramsey July 1, 1941 2,310,069 Fahnoe Feb. 2, 1943 2,318,817 Triplett May 11, 1943 2,319,276 'Iriplett May 18, 1943 2,333,774 Fahnoe Nov. 9, 1943 2,379,200 Triplett June 26, 1945 2,403,121 Rawlins et a1 July 2, 1946 2,567,236 Rawlins et a1 Sept. 11, 1951 

